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A126206 Number of 4's in the decimal expansion of 4^n. 7
0, 1, 0, 1, 0, 1, 1, 1, 0, 2, 1, 3, 0, 1, 2, 2, 2, 1, 1, 3, 0, 3, 3, 3, 2, 2, 2, 3, 1, 2, 2, 3, 4, 3, 1, 3, 3, 4, 2, 4, 2, 4, 2, 2, 3, 4, 3, 3, 3, 3, 2, 2, 3, 5, 2, 4, 2, 4, 4, 3, 3, 3, 4, 4, 6, 5, 5, 4, 2, 9, 5, 2, 4, 6, 4, 7, 4, 2, 5, 4, 3, 4, 8, 4, 7, 9, 2, 8, 4, 7, 3, 10, 9, 5, 3, 5, 8, 8, 3, 10, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,10
LINKS
EXAMPLE
a(11)=3 because 4^11 = 4194304 with three 4's.
MAPLE
P:=proc(n) local i, k, x, y, w, cont; y:=4; k:=y; for i from 0 by 1 to n do x:=y^i; cont:=0; while x>0 do w:=x-trunc(x/10)*10; if w=k then cont:=cont+1; fi; x:=trunc(x/10); od; print(cont); od; end: P(100);
# Alternative:
map(n -> numboccur(4, convert(4^n, base, 10)), [$0..100]); # Robert Israel, Jul 18 2018
MATHEMATICA
DigitCount[4^#, 10, 4]&/@Range[0, 150] (* Harvey P. Dale, Feb 01 2011 *)
CROSSREFS
Sequence in context: A228786 A140699 A140256 * A307744 A119709 A328167
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified March 28 13:42 EDT 2024. Contains 371254 sequences. (Running on oeis4.)